This invention pertains to a vacuum pump system.
Vacuum processes in closed systems must typically either reach a predetermined absolute low pressure within the shortest possible time and stay at this pressure level, or they have to follow a specific predetermined pattern of pressure changes. In the past, pressure variations have been accomplished by manual or automatic operation of valves.
Piston pumps are advantageously used in vacuum systems for evacuation of containers and for maintaining very low pressures in containers. These pumps are highly reliable because of their lack of valves and generally simple construction. However, one disadvantage of cylinder piston pumps is that they are extraordinarily noisy during operation at slight underpressures, that is, during the beginning of evacuation of a container. This occurs because the drive motor is subjected to substantial stresses and the cylinder piston pump is subjected to considerable thermal stress.